É possível que todo M tenha um nome começando com M?

Nem sempre, mas quase:

Para M Bernard Lee , foi sugerido que seu nome verdadeiro é como o seu colega de quadrinhos, Sir Miles Messervy.

While his name was hinted at throughout the novel series and finally revealed in The Man with the Golden Gun, in the film series only his first name, Miles, was revealed in The Spy Who Loved Me. - wikia

Para o caso de Robert Brown , é mais complicado, pois nunca foi explicitamente declarado que ele continuou o papel do Almirante Hargreavesin de O Espião Que Me Amava ou continuou o papel de Bernard Lee. Mas se ele jogar como Hargreavesin, isso sugere seu rebaixamento:

One thing to note is that in the pre-title credits to The Living Daylights, M's insignia suggests he is a Rear Admiral, which would mean if he was Hargreaves then he was demoted since Hargreaves' insignia in The Spy Who Loved Me suggests he is a Vice Admiral. - wikia

Para a versão de Judi Dench , não seu primeiro nome, mas seu sobrenome começa com M, de dailymail.co.uk :

During the scene, Bond, played by Daniel Craig, is handed a box containing a Royal Doulton bulldog draped in a British flag, which is usually kept on M’s desk.

Zooming in on the box’s inscription, the words ‘From the Estate of Olivia Mansfield Bequeathed to James Bond’ are visible.

Até mesmo as autoridades confirmaram:

Meg Simmons, archive director for Bond production company Eon, said: ‘We’ve searched around and as far as we can see this is the first and only time anyone’s ever revealed M’s real name.

‘It may not have been spoken, but if you were watching on a big enough screen it could have been visible, so we’d argue it’s now canon.’

E para Ralph Fiennes você já sabe que o nome dele é Mallory.

Nota: Mas lembre-se nos romances originais de Fleming, havia apenas um M que foi revelado para ser chamado Vice-Almirante Sir Miles Messervy KCMG, CB, DSO, OBE .